Wireless communication systems, such as the 2nd Generation (2G) (otherwise referred to as Global System for Mobile (GSM) communications) and the 3rd Generation (3G) of mobile telephone standards and technology, are well known. An example of such 3G standards and technology is the Universal Mobile Telecommunications System (UMTS), developed by the 3rd Generation Partnership Project (3GPP) (www.3gpp.org).
Typically, wireless communication units, or User Equipment (UE) as they are often referred to in 3G parlance, communicate with a Core Network (CN) of the 3G wireless communication system via a Radio Network Subsystem (RNS). A wireless communication system typically comprises a plurality of radio network subsystems, each radio network subsystem comprising one or more base stations, each base station supporting one or more communication cells to which UEs may attach, and thereby connect to the network.
The practice of geolocation, in relation to such wireless communication systems, is the identification of a real-world geographical location of a wireless communication unit. Geolocation may be used for various different purposes ranging from, by way of example, enabling emergency services to determine the location of a caller during an emergency call, to enabling network coverage, quality of service and other similar wireless communication unit related data to be evaluated, etc.
A number of techniques for performing geolocation of wireless communication units in a wireless communication system have been developed. One such technique involves the installation of dedicated hardware at each base station site, as currently implemented for ‘E911’ emergency call location in the United States of America. Such a technique enables a high level of accuracy for geographically locating a wireless communication unit. However, the installation of such additional, dedicated hardware is expensive to implement.
Another technique uses GPS (Global Position Satellite) functionality built into wireless communication units. This technique also enables a high level of accuracy for geographically locating a wireless communication unit. However, this technique relies on the wireless communication unit being geolocated to have a GPS receiver, and for that GPS receiver to be turned on. Even if a GPS receiver is present, many users leave them turned off due to privacy concerns and/or to prolong battery life.
A further technique uses signal strength and timing data derived from the wireless communication unit itself, along with network configuration data provided by the network operator, to locate the wireless communication unit. One such technique is described in the applicants co-pending patent application WO2010/083943. Advantageously, this technique does not require additional dedicated hardware to be implemented within the network, nor does it require GPS functionality to be available within the wireless communication unit being located. However, a problem with such a technique is that it relies on signal strength and timing data provided by wireless communication units, which are consumer grade devices built to a budget, and which typically do not undergo regular calibration. Furthermore, such consumer units often experience rough treatment such as being dropped on hard surfaces etc. As such, the data received from wireless communication units can be unreliable, and may even be entirely inaccurate. A further problem with such a technique is that it relies on network configuration data provided by the network operator; such data sometimes being out of date or simply inaccurate.
Thus, there is a need for an improved method and apparatus for geolocating a wireless communication unit, whereby at least some of the above mentioned problems with known techniques are substantially alleviated.